On Friday 28 November 2008 18:09:37 Joshua Murphy wrote: > On Fri, Nov 28, 2008 at 6:46 AM, Alan McKinnon <[EMAIL PROTECTED]> wrote: > > On Friday 28 November 2008 13:14:42 Dale wrote: > >> If this is a little high, what would be the best way to defrag it? > > > > By not defragging it. > > > > It's not Windows. Windows boxes needs defragging not because > > fragmentation is a huge problem in itself, but because windows > > filesystems are a steaming mess of [EMAIL PROTECTED] that do little right > > and most > > things wrong. Defrag treats the symptom, not the cause :-) > > > > Reiser tends to self-balance itself out. What is especially noteworthy is > > that none of the general purpose Linux filesystems provide a defrag > > utility. Theodore 'Tso and Hans Reiser are both exceptional programmers, > > if there was a need for such a tool they would assuredly have written > > one. They did not, so there probably isn't. > > > > Any Linux defrag tool you encounter will have been written by a third > > party separate from the developers. It will move blocks around and update > > superblocks, the drive will have to be unmounted for that to work and a > > slight misunderstanding of how to do it will ruin data. > > > > Are you willing to take the very real risk of data corruption? > > > >> Is > >> there a best way? I do have a second hard drive that I back up too. > >> Both Drives are 80Gbs and I do have a set of DVD back ups as well. I > >> can update those pretty quick. > > > > -- > > alan dot mckinnon at gmail dot com > > While not trying to incite flames here... xfs isn't general purpose? > xfs_fsr defrags xfs partitions while they're mounted and is designed > to be used from cron (it's in xfsdump, not xfsprogs). File > fragmentation, while a fact of life on any filesystem that sees any > real use, does slow access times, as the drive head has to jump from > one place to another, so a lot of fragmentation is a bad thing...
On a proper multi-user multitasking OS like Unixes, the heads are going to be moving around all over the disk partition anyway just in general usage, even with zero file fragmentation. How much extra movement does fragmentation introduce? I've been waiting for a proper statistical analysis of this question for years. I'm still waiting :-) Besides, modern storage presents an extra wrinkle. Defrag as most of the world knows it originated in DOS, where disk sectors were guaranteed to be laid out on disk in the order of their sector number. These days we have no such guarantee, and you cannot really be sure if blocks are laid out contiguously on-disk just by looking at the blocks numbers. I don't know of any filesystem tool that knows how to interrogate a drive's firmware and get it right for every storage type out there. > but > as you say, we're not dealing with FAT based FS's here, so severe > fragmentation only shows itself on very full filesystems. I very > rarely see over 80% usage of my filesystems and have never > consistently checked fragmentation levels, though, so I can't say > whether xfs's being the exception on having a tool for the job means > it particularly needed one... -- alan dot mckinnon at gmail dot com
